The protection of Brassica species from weeds and other vegetation which inhibit the growth of the Brassica species is a constantly recurring problem. To help combat this problem, researchers in the field of synthetic chemistry have produced an extensive variety of chemicals and chemical formulations effective in the control of such unwanted growth. Chemical herbicides of many types have been disclosed in the literature and a large number are in commercial use. Such herbicides, however, can injure the Brassica species in addition to the weeds and other vegetation intended to be controlled.